Examples of prior-art semiconductor inspection device configurations include the configuration described in JP-T-2005-517906. This prior-art inspection device has a dark-field detection optical system that illuminates a wafer surface with laser light obliquely and detects the light scattered from the wafer surface. The optical system employs off-axis illumination in which the laser light is emitted from the outside of an objective lens. During off-axis illumination, if the optical system includes vertical detection optics having an optical axis parallel to a normal line relative to the surface of the wafer, the system needs to have a low elevation angle for illumination due to mechanical restrictions associated with disposition of the vertical detection optics.
On the other hand, JP-A-2000-2664 describes through-the-lens (TTL) illumination in which light is emitted through an objective lens having an optical axis vertical to a wafer. In the TTL illumination, the wafer can be illuminated substantially vertically.